Magnetic resonance imaging (MRI) is a type of imaging that does not require radiation and produces very detailed images of certain tissues. It can be a useful addition to breast cancer screening for some women. The American Cancer Society and the American Congress of Obstetricians and Gynecologists (ACOG) recommends screening breast MRI for women who have a greater than 20% lifetime risk of developing breast cancer. Who falls into this category?
- Women with a known BRCA1 or BRCA2 gene mutation. This is a mutation that dramatically
increases the risk of breast cancer. Women with a BRCA1 mutation have a 55-65% risk of developing breast cancer by the age of 70 and those with BRCA2 have a 45-47% risk of breast cancer by the age of 70.
- Women who have a 1st degree relative (mother or sister) with a known BRCA1 or BRCA2 mutation but have not yet been tested themselves.
- History of radiation to the chest between the ages of 10 and 30. This would ypically have happened during treatment for cancer (the only non genetic indication).
- A lifetime risk of breast cancer of 20% of higher based on a risk assessment tool such as BRCAPRO, BODACEA, or Claus (the Gail model is not recommended for risk assessment for MRI). A genetic counselor is the most appropriate person to apply one of these risk assessment tools.
- A genetic syndrome that is associated with breast cancer risk, such as Li-Fraumeni, Cowden, or Bannayan-Riley-Ruvalcaba (or a 1st degree family member with one of these syndromes).
Why shouldn’t everyone get a breast MRI? Well, it’s expensive, involves intravenous injection of a contrast material called gadolinium that is associated with certain risks, and there is no data to say it offers a benefit to women at average risk. There are other indications for breast MRI for women distinct from screening, such as for women with breast cancer to assist in staging the disease or monitoring results of chemotherapy and MRI can also help in the diagnosis of capsule rupture with a silicone breast implant.
Whether you should be tested for a BRCA 1 or BRCA 2 genetic mutation depends mostly on family history. According to the National Cancer Institute testing is typically offered for women with:
- two first-degree relatives (mother, daughter, or sister) diagnosed with breast cancer, one of whom was diagnosed at age 50 or younger;
- three or more first-degree or second-degree (grandmother or aunt) relatives diagnosed with breast cancer regardless of their age at diagnosis
- a combination of first- and second-degree relatives diagnosed with breast cancer and ovarian cancer (one cancer type per person)
- a first-degree relative with cancer diagnosed in both breasts (bilateral breast cancer)
- a combination of two or more first- or second-degree relatives diagnosed with ovarian cancer regardless of age at diagnosis
- a first- or second-degree relative diagnosed with both breast and ovarian cancer regardless of age at diagnosis
- breast cancer diagnosed in a male relative (a man with breast cancer has a BRCA2 mutation until proven otherwise with negative testing).
Women of Ashkenazi Jewish descent are 5 times more likely to carry a BRCA1 or 2 mutation and so the threshold for testing is lower:
- any first-degree relative with breast or ovarian cancer
- two second-degree relatives on the same side of the family diagnosed with breast or ovarian cancer.
Genetic counseling is recommended before and after BRCA1 and 2 testing, so if you fit into one of the risk categories above don’t ask your doctor to be tested, ask for a referral to a genetic counselor. A genetic counselor will confirm, after a detailed family history, if you are truly at risk and if testing is indeed indicated (they may even recommend addition tests depending on your history), but they will also review the limitations of testing and the implications of a positive and a negative result.
Remember, this post is not direct medical advice